In order to test the integrity of an integrated circuit, the typical integrated circuit chip is fabricated having a plurality of metal input and output pads along its periphery. From a practical standpoint, it is important to test the integrated circuit prior to use in order to insure the integrity of the chip. Generally, the dimensions of the pads are 4.times.4 mils and the pads will be wire bonded to connect the integrated circuit to the package.
In practice, a probe card is used for testing purposes. The probe card is generally a printed circuit board having a plurality of metal fingers extending therefrom which are designed to mate with the input and output pads on the integrated circuit to be tested. These metal fingers are brought into contact with the input and output pads in order for the probe card to send messages to and receive messages from the integrated circuit. Signals are sent through the integrated circuit to determine its integrity by controlling the input and output of the probe card signals. These signals are subsequently analyzed by a testing system to determine whether the chip is useful.
Unfortunately, when using the probe card, it is difficult to precisely align the probe card fingers with the integrated circuit pads. In the past, once the card has been used several times, it is necessary to realign the card and resharpen the points in order to have contact for proper testing of the integrated circuit. Generally, probe cards are sent to a third party vendor which specializes in realigning probe cards to insure their integrity, a process which can be costly and time-consuming.
The testing of the integrated circuit card can experience problems other than nonalignment, such as the formation of a thin oxide layer which is still present on the pad prior to testing. Unfortunately, false negative tests are experienced when there is no electrical contact between the fingers on the probe card and the integrated circuit.
Therefore, a need has arisen in the industry to provide a method and apparatus for testing integrated circuits and for eliminating the cumbersome task of aligning the probe card fingers to the input and output pads on integrated circuits.